<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>弹出警告对话框</title>
</head>
<body>
    <button onclick="showAlert()">运行程序</button>

    <script>
        function showAlert() {
            alert("Hello 欢迎学习JavaScript!");
        }
    </script>
</body>
</html>